The present application is based on Japanese Patent Application No. 2002-352130, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a chain-type fusible link for a large current including fuse circuit-forming members each having terminal portions interconnected in a chain-like manner through respective fusible portions, and also relates to a method of producing this fusible link.
2. Related Art
FIG. 5 shows one conventional fusible link of the type described. This fusible link 1 comprises first and second fuse circuit-forming members 3 and 4, and a box-shaped housing 2 (made of a synthetic resin) in which these fuse circuit-forming members 3 and 4 mounted.
The first fuse circuit-forming member 3 includes an interconnecting plate portion 3a, a plurality of terminal portions 3c and 3cxe2x80x2 connected to the interconnecting plate portion 3a through respective fusible portions 3b, a battery terminal 3d extending from one end of the interconnecting plate portion 3a, and a common terminal portion 5a connected to the other end of the interconnecting plate portion 3a through a fusible portion (not shown). This first fuse circuit-forming member 3 is formed by pressing an electrically-conductive flat plate (not shown).
The second fuse circuit-forming member 4 includes an interconnecting plate portion 4a, a plurality of terminal portions 4c and 4cxe2x80x2 connected to the interconnecting plate portion 4a through respective fusible portions 4b, and a common terminal portion 5b extending from an end of the interconnecting plate portion 4a. This second fuse circuit-forming member 4 is formed by pressing an electrically-conductive flat plate (not shown), separately from the first fuse circuit-forming member 3.
The housing 5 has a generally rectangular parallelepiped shape, and has a circuit member-receiving chamber 2b formed therein, and this chamber 2b has an opening 2a formed in an upper side of the housing. A plurality of connector housing portions 2c and a plurality of terminal support portions 2d are formed at a lower side of the circuit member-receiving chamber 2b. The opening 2a in the housing 2 is closed by a lid 6.
In the above construction, the first and second fuse circuit-forming members 3 and 4 are inserted into the circuit member-receiving chamber 2b through the opening 2a in the housing 2. When the first and second fuse circuit-forming members 3 and 4 are completely received in the circuit member-receiving chamber 2b, the interconnecting plate portions 3a and 4a of the first and second fuse circuit-forming members 3 and 4 are located in the circuit member-receiving chamber 2b, and also the terminal portions 3c, 3cxe2x80x2, 4c and 4cxe2x80x2 are set in their respectively predetermined positions in the connector housing portions 2c and terminal support portions 2d. 
Then, the common terminal portions 5a and 5b of the first and second fuse circuit-forming members 3 and 4 are fastened to the housing by a bolt 7. As a result, the first and second fuse-forming members 3 and 4 are electrically connected together, so that desired fuse circuits are formed by the first and second fuse circuit-forming members 3 and 4.
The battery terminal 3d of the first fuse circuit-forming member 3 is fastened to the housing 2 by a bolt (not shown). A terminal of a battery cable (not shown) is connected to the battery terminal 3d, and terminals of each of mating connectors are connected respectively to the terminal portions 3c and 4c in the corresponding connector housing 2c, and LA terminals (not shown) are connected by screw-fastening respectively to the terminal portions 3cxe2x80x2 and 4cxe2x80x2 received in the terminal support portions 2d. The terminals of the mating connectors and the LA terminals are connected to loads via cables (not shown), and electric power is distributed and supplied from a battery to these loads via the fuse circuits.
When a current of above a predetermined value flows through any of the fusible portion 3b, 4b, for example, in the event of a short-circuiting accident on the part of the corresponding load, the fusible portion 3b, 4b is heated to be melted, thereby preventing an accident due to such excess current.
JP-A-2000-133114 shows another conventional fusible link.
In the above conventional fusible link 1, however, the flat plate-like first and second circuit-forming members 3 and 4, formed separately from each other, were mounted in the housing 2 to form a unit, and therefore the assembling operation was cumbersome, and besides the overall size was large. Particularly, it was necessary to secure a space for a mounting jig for mounting the first and second fuse circuit-forming members 3 and 4 in the circuit member-receiving chamber 2b in the housing 2, and therefore the compact design was limited. Furthermore, when the number of the fuse circuits was increased, the housing of a large size must be used.
This invention has been made in order to solve the above problems, and an object of the invention is to provide a fusible link, in which a sufficient number of fuse circuits can be secured, and the overall size can be made small, and also to provide a method of producing this fusible link.
(1) The invention is directed to a fusible link including a plurality of fuse circuit-forming members each having a plurality of terminal portions which are arranged in a chain-like manner, and are connected to an interconnecting plate portion through respective fusible portions, and the plurality of fuse circuit-forming members being mounted on a housing to form large-current fuse circuits; characterized in that a bending portion is formed integrally at a generally central portion of the interconnecting plate portion, and the fuse circuit-forming members are formed integrally respectively at opposite sides of the bending portion, and the bending portion and the fuse circuit-forming members are formed by an electrically-conductive flat plate; and insulating housings, forming the housing, are formed integrally respectively on the fuse circuit-forming members by insert molding; and the bending portion is bent at its predetermined portion in such a manner that the housings are disposed in parallel opposed relation to each other.
In this fusible link, the bending portion of the interconnecting plate portion is bent at its predetermined portion in such a manner that the two housings, formed integrally respectively (by insert molding) on the fuse circuit-forming members provided respectively at the opposite sides of the bending portion, are disposed in parallel opposed relation to each other. Therefore, by bending the single flat plate, the fuse circuits, generally equal in number to fuse circuits obtained with two plate plates, can be secured. And besides, it is not necessary to secure a space for a mounting jig for mounting the pair of circuit-forming members in the housing, and therefore the whole of the fusible link can be formed into a compact design.
(2) The fusible link of the invention is further characterized in that a plurality of ribs are formed integrally with and project from an outer surface of each of the housings in such a manner that the two adjacent ribs are disposed respectively at opposite sides of each of the terminal portions in opposed relation to each other.
In this fusible link, a terminal receiving portion for receiving a mating terminal for connection to the terminal portion is formed between the opposed ribs disposed respectively at the opposite sides of each terminal portion.
(3) The fusible link of the invention is further characterized in that a retaining portion is formed on one of the two housings, while an engagement portion for retaining engagement with the retaining portion to hold the housings in parallel opposed relation to each other is formed on the other housing.
In this fusible link, when the bending portion is bent, the retaining portion on the one housing is retainingly engaged with the engagement portion on the other housing, thereby positively holding the two housings in parallel opposed relation to each other.
(4) The invention is directed to a method of producing a fusible link including a plurality of fuse circuit-forming members each having a plurality of terminal portions which are arranged in a chain-like manner, and are connected to an interconnecting plate portion through respective fusible portions, the plurality of fuse circuit-forming members being mounted on a housing to form large-current fuse circuits; characterized in that a bus bar is formed by pressing a single electrically-conductive flat plate in such a manner that a bending portion is formed at a generally central portion of the flat plate while the fuse circuit-forming members are formed respectively at opposite sides of the bending portion, and subsequently insulating housings, forming the housing, are formed integrally respectively on the fuse circuit-forming members, provided respectively at the opposite sides of the bending portion of the bus bar, by insert molding; and subsequently the bending portion of the bus bar is bent at its predetermined portion in such a manner that the housings are disposed in parallel opposed relation to each other while a retaining portion of one of the two housings is retainingly engaged with an engagement portion of the other housing, thereby assembling and producing the fusible link.
In this fusible link-producing method, the fusible links can be mass-produced at low costs merely by effecting the simple operation in which the bending portion of the bus bar is bent at its predetermined portion in such a manner that the two housings, provided respectively at the opposite sides of the bending portion, are disposed in parallel opposed relation to each other.